We propose to analyze the functional significance of nonHLA-A,B,-C class I genes. Of the several such genes isolated in our laboratory as genomic and cDNA clones, the studies here will be focussed on one particular clone, designated RS5. We have carried out a substantial amount of preliminary studies on this clone and an account of these studies is briefly summarized. We will generate serological reagents for the RS5 encoded protein by using vaccinia virus expression vector system. The antisera will be generated by immunizing the HLA transgenic mice with the recombinant vaccinia viruses containing the RS5 cDNA. The specific antisera thus generated will be used in immunoprecipitations and functional studies. A transfection system has been devised in which we will study the physical association between the RS5 encoded protein and the CD8. The transgenic mice have been made that contain the gene RS5. These mice will be used as model system to design and execute the functional analyses of the introduced RS5 gene. Since there is lack of sufficient data to attribute any functional role to this gene, the knowledge of the tissue specificity of th expression of this gene in the transgenic mice will help in designing more appropriate experiments to assess the impact of the RS5 encoded protein on the immune system of the recipient mice. There is an extremely high level of conservation in the backbone structure of the RS5 encoded protein and that of the well studied HLA-A,- B,and -C locus derived proteins and, therefore, the RS5 encoded protein is expected to bind either the Alpha-Beta T cell receptor or a receptor system of highly homologous nature. The Gamma-Delta receptor is not restricted by the classical class I proteins and it may be a strong candidate for the nonclassical class i proteins such as that encoded by the gene RS5. There are however, several other known heterodimeric molecules on the surface of the T cells with structures similar to the Alpha-Beta receptors and which have no known specificity. The experiments are designed to undertake the molecular analyses of the T cell receptor repertoire in the transgenic mice in response to the introduced gene. Subtraction cDNA cloning strategy ins planned to identify the receptors if they do not belong th the Alpha-Beta or Gamma-Delta category.